


The Advantage of Rotterdam Morgenstern

by Mariana_Monteverde



Series: Coffee Cups & Reveries [1]
Category: Harry Potter - J. K. Rowling
Genre: Aurors, Black Family Drama (Harry Potter), F/M, Family Bonding, Family Dynamics, Family Feels, Family Loss, Friendship, Implied/Referenced Character Death, Meet the Family, Minor Character Death, Mother-Son Relationship, Owls, The Noble and Most Ancient House of Black
Language: English
Status: Completed
Published: 2020-08-13
Updated: 2021-01-15
Packaged: 2021-03-05 23:21:05
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 6
Words: 8,028
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25883524
Author URL: https://archiveofourown.org/users/Mariana_Monteverde/pseuds/Mariana_Monteverde
Summary: Advantage (noun) /ədˈvɑːn.tɪdʒ/a condition giving a greater chance of success.The Morgenstern Family arrived at England in 1910, when Matilda Morgenstern, a seer, saw the downfall of the German Empire, and how even the Wizard folk would not stay untouched.Rotterdam Morgenstern is her grandson, the first Morgenstern to be born in England, son of a german wizard and an English witch, he does not possess his grandmother's gift, but he has other talents that will grant him and those he favours an Advantage.
Relationships: Ignatius Prewett/Lucretia Black Prewett, Original Female Character/Original Male Character
Series: Coffee Cups & Reveries [1]
Series URL: https://archiveofourown.org/series/1878247
Comments: 20
Kudos: 8





	1. Inception

**Author's Note:**

> Hi! Hope everything is going well with you!  
> I'm not sure if anyone will ever read the story about the wizard family I created in this wizard world!
> 
> It all started with a headcanon, of a witch born in 1977, but for that to make sense, you must first know the story of her family, and it all starts with Rotterdam Morgenstern.  
> But Rotterdam Morgenstern Story does not start with him...
> 
> I hope you enjoy this as much as I do!

The Morgenstern Family arrived at England in 1910, when Matilda Morgenstern, a seer, saw the downfall of the German Empire, and how even the Wizard folk would not stay untouched. And so, along with her husband, Friedel, and their son, Ansel, she brought the family to England, to a small town called Pilling and where it was erected and warded Morgenstern Manor.

Mathilda preferred to live a secluded lifestyle, always had. Never engaging in society, distancing herself from other wizard families, pureblood or not, that might have been the reason she chose a city not known to be home to any other magical family. 

* * * * * * * * * *

Ansel Morgenstern was taught by his mother and the father to the best of their abilities. In Germany, he had had tutors, but his mother did not trust anyone here to arrange one, so he studied and practised to the best of his abilities from home. But Ansel wanted so much more to his life than to live at Morgenstern Manor. He wanted to achieve something by his own wand!

Only with his mother passing in 1920 did he pursued his dreams, at age 28. It all started with sending a letter to the office of magical education, identifying himself and expressing his desire to be examined and get some credentials to follow a career at the ministry. And that happened rather quickly, after so many years enclosed on the house, he excelled at most of the subjects, passing his WOMBAT with an outstanding, being given 12 O's on his OWL's and 12 O's on his NEWT's, whatever that meant. 

There was only one thing Ansel Morgenstern was average at, Duelling, mostly because his parents were very polite and pacifists, and would not entertain him on duelling or allowing his tutors to do it. And so, Ansel Morgenstern chose the department that would help him improve the best in that field, the Department of Magica Law Enforcement and the Auror Office. He thought about leaving Pilling and moving to London, to be closer to the Ministry and St Mungos. Still, he wanted to honour his mother dream of establishing the Morgenstern Family in Pilling, and someone needed to care for the bloody owls his father had bred with such love through so many years, that had come from Germany with them. 

And so he remained at Pilling, but he installed a Floo connection, something that they did not have in Germany, so it was a fantastic learning experience. He would Floo to the Ministry; he would Floo to Diagon Alley, and he would Floo to his colleagues’ houses, whenever he invited of course. 

* * * * * * * * * *

After many dinners hosted by his colleagues and their special others, Ansel took it upon himself to host one at Morgenstern Manor, but not just any kind of small dinner, a big party.

And it was during that grand event that he met Marbella Moody, brought as a plus one of a receptionist at the DMLE, he found the woman outside by the Owlery, petting one of the owls. 

“They seem very fond of you, madam, I must confess they try to bite me whenever I even try to stroke their feathers to clean them,” he said taking a long drag from a cigar.

“I apologise, I did not know the owlery was out of boundaries,” she said.

“No, madam, I just did not get myself the trouble of clean it, because I did not think anyone would come here.” 

“You have a lovely home, Mr Morgenstern, honestly, I’m not here because it’s distasteful.” she assured looking down “I don’t usually engage in these parties, I must confess.”

“And why would not a young lady enjoy such festivities?” he asked summoning a bag of treats for the owls.

“I must admit I am not the biggest fan of the loud music and the crowds, and the different conversations…” she said sighing, giving one treat to Zugzpite “I do enjoy the silence or smaller groups.”

“Or the company of animals” he mentioned. 

“Or the company of animals” she agreed. “Your owls are magnificent, Mr Morgenstern.”

He was amazed by her declaration “Do you not think they’re terrifying, Miss…”

“Moody, Marbella Moody, sir. And no, they’re enormous, but they’re not terrifying, they’re so gentle. I sat down there where you are standing, and this one started to hoot to me and came to stroke me with its wing.”

“You’re a soft boy, Zugzpite, is it just for the ladies?” he teased. “Because whenever I approach, I think you want to rip one of my fingers or my wand.” 

“Zugzpite” she repeated, failing terribly at the accent, but the owl nestled itself closer to her.

And then there was what sounded like an explosion “Was zur Hölle?” he cursed looking inside the manor.

“I think you should go do some damage control, Mr Morgenstern, before your beautiful manor burns to the ground.” 

“Another time then, Miss Moody, enjoy the rest of the night.” 

When Ansel woke up the next morning, there was an insistent knock on both his window and his door. “Verdammt” he cursed once again, groaning into his pillow, and with a twist of his wand both the window and the door opened. A small owl flew inside, holding a message to him, and at the door, there were two house-elves. 

“Dear Mr Morgenstern.

I hope you forgive me for having left without biding my farewell. 

I noticed you did not own any house-elf, as to atone to my abrupt departure, I’m lending you two of the family elves for the day, they will help you clean the manor and the grounds.

Best Wishes, Marbella Moody.”

The owl did not wait for a reply or a treat before it flew away through the window.

“We might start cleaning, yes, sir?” one of the elves asked.

“Yes, yes, thank you,” he said, moving to take a bath and wishing for a large cup of coffee.

* * * * * * * * * *

Ansel corresponded by owl with Marbella for weeks before starting his courtship. He still did not understand how he had taken a liking to the young woman. Marbella who had left his loud party to sit by the owls, but also Marbella who the next morning had sent her elves to help clean his manor. 

What had someone once told him, we are somehow attracted to people who resemble our parents. And so he was starting to cherish all the moments he spent with a young woman, whose beauty was rather ordinary, but whose kindness and awareness knew no boundaries. 

He married Marbella 7 months after that party, the first and last grand party at Morgenstern Manor. They hosted small dinners, and similar lunches, brunches and birthdays, but never something as big.

* * * * * * * * * *

Rotterdam Gabriel Morgenstern was born in June 7th 1929, only heir to Morgenstern Pure-blood Wizarding Family, son of Ansel Morgenstern and Marbella Morgenstern (née Moody).

**Notes for the Chapter:**

> I hope you enjoyed this story!  
> I created Rotterdam Morgenstern years ago, but Ansel, Marbella, Mathilda and Friedel only appeared today!  
> I had no intention of creating these characters, but here they are!
> 
> Some translations:  
> Was zur Hölle? – What the hell?  
> Verdammt! = Damn!/Dammit
> 
> Neither English nor German is my first language so if you notice any mistakes, please say!


	2. Overindulgence

**Summary for the Chapter:**

> How the childhood of Rotterdam Morgenstern contributed to his advantage.

Rotterdam Morgenster grew up in a happy home with a loving family, a father who loved him and gave him enough liberty to grow independent and a mother who cherished him like he was the most precious thing in the world.

All the adventures his father would take him, and his mother was always close, ready to soothe him. 

* * * * * * * * * *

When he was three years old, Ansel got him his first little broom, charmed to fly 50 cms from the ground, and brought a large bouquet as well, an apology to his wife. He had seen the broom during a surveillance mission on Diagon Alley, and he knew he must gift it to his son. 

“Rotte, come here, Vati has something for you,” he said from the drawing-room as soon as he stepped out of the Floo.

The boy appeared quickly coming from the garden and throwing himself at his father’s arms “Daddy!” he said with a huge grin.

And a few seconds later, Marbella appeared after the child, and she had a massive smile until her eyes fallen on the flowers “You have done something, have you not, Ansel?” 

He walked to his wife and kissed her forehead before giving her the bouquet. “You always forgive me in the end” he whispered, putting Rotterdam on the floor and kneeling in front of him. He took the little broom from his Auror robes and returning it to its correct size. 

“Broom,” Rotterdam said with a huge grin and clapped its hands.

“Ansel Conrad Morgenstern” she called “we did not discuss this beforehand. A broom is very dangerous.”

“It does not even fly to his height, Marby, it will help with balance and posture, and all those wonderful things you want to teach him, how to be responsible, how never to give up. He’s been so good for us, has he not?” 

“The best,” she said kneeling as well and stroking her child fringe as he held the broom on his hands, his eyes glued to the flying instrument. “What if he gets hurt?”

“His mommy and his daddy will be around to… how do you say it” Ansel stopped to think “Lick it better?”

She chuckled “Kiss it better” she corrected. 

“Oh… is it that simple, just kiss it better?” he asked, pulling his wife down, so she was laying on top of him and kissed her nose “Better? or-” he kissed her lips “better now?”

Marbella rolled her eyes, but she was smiling, and Rotterdam had thrown himself on top of her. “you’re so sneaky, Ansel Morgenstern, you would have been a Slytherin if you had attended Hogwarts.”

“Is that good? What were you, dear?” he asked, stroking her hair behind her ear, as it had fallen from the chignon on the back of Marbella’s head. 

“All the houses are good, some are more cunning than others” she whispered, “I was on Ravenclaw.”

“And what does differentiate Ravenclaw from the other houses?” he asked.

“Nonconformity,” she said.

“That you are, sweetheart, you are not like anyone I met before… you show me that every day” he said, kissing her one more time before getting up “So… can I show Rotte how to fly? Fifty cms from the ground?”

Marbella raised from the floor, kissed her son’s forehead “You kiss it better first when he falls, Ansel.”

And when a few minutes later, Rotterdam tumbled down from his little broom and started wailing, Ansel, Merlin bless him, he tried to kiss it better, but the boy kept crying. “I don’t think father kisses have the same magic as mothers.” 

“Come here, little boy, mommy will kiss it all better, where does it hurt?” She said, kissing all over the place until the boy was laughing.

“Magic,” Ansel said as if he could not believe it. 

* * * * * * * * * *

Ansel Morgenstern had always thought he wanted to live his life to the fullest, work during the week, meet his colleagues and friends for drinks that only ended the next day.

But there was something beautiful about coming home after a glass of firewhiskey, picking a mug of coffee from an elf and finding one’s wife reading the same silly stories about magical creatures to one’s son.

How he should never tickle a sleeping dragon, and how the squid on the bottom of the lake was friendly and loved peanut butter spread on bread. And so many other nonsensical stories.

And he would always listen from the doorway before making his way to kiss his son’s forehead and tucking him in. 

He also had never believed he would cherish a woman like Marbella, the quiet woman who at parties and dinners would always find the most peaceful spot on the room or walk outside, away from the noise, so opposite from him. 

But here he was, sitting on their bed against the headboard and watching his wife brushing her hair, sitting by the mirror, smiling like a fool. Suppose her pregnancy with Rotterdam had not been so hard if she had not been miserable and sick and in pain most of the time, he would push for another. But he could not bear the impotence of not being able to soothe her agony. Again. 

And so he was content, happy, blessed, fulfilled with all he had.

“You’re doing it again, Ansel.”

“Doing what?”

“That… with your eyes… while you watch me.”

* * * * * * * * * *

When he was six years old, his father took him for a stroll around Diagon Alley. And they stopped for some ice cream at Fortescue’s, but Rotterdam eyes were not on the hundred flavours of ice cream, they were glued to a store across the street.

The store across the street was the Magical Menagerie. And this is the tale, how that afternoon the Morgensterns turned proud owners of a Double-ended Newt, a Giant Purple Toad, a Streeler, and not one, but two Puffskeins.

Marbella Morgenstern truly wanted to be mad when she came back from visiting a friend, Catherine Bulstrode (who would soon deliver her first child). And she almost floo back to her friend house and told her children and their fathers were a nightmare. 

But Marby stayed still watching her Auror husband play with a Puffskein. 

And she suddenly remembered, it was not like the fact ever left her, that he had never had this kind of childhood. Strict parents, living far away from everyone and everything, with only owls around and to not even be able to play with them, to raise and bred again.

“Sweetheart!” he called seeing her by the fireplace “Had you ever seen of these?” he asked, throwing the little beast up and catching it again. 

“Mommy, mommy. Look at all the different animals! That lizard has two heads and no tail! And that frog is so purple, mommy, it looks like a large plum! And the snail changes colours, but he must remain in the aquarium because the slime is yucky and we cannot touch! And this is Odie” he showed her the Puffskein cuddling on his shirt.

Marbella nodded with a smile, she understood that her husband tried to give Rotterdam all the things he never had on his childhood, indulging him like that. “So many animals, but you did not buy a cat, how is that possible?” she asked, barely catching Ansel’s Puffskein when he threw it at her. She stroked the soft fur with a smile. She remembered having one when she was young.

“A cat, Marby? But we have owls, how could we have a cat?” he asked.

And she was about to say that they could ward the owlery, but she dropped it, it was one of those preconceived ideas of Ansel. So she just smiled “Silly me, of course,” she said, pecking his cheek. “And what do you call your Puffskein?”

“Well, I thought about calling it Marby so that I could carry it everywhere” he started. Marbella just gave him a look “But I love our bed too much to sleep in another room because of it, so I called it Zart” he explained kissing her forehead before taking the little beast from her arms and running away.

* * * * * * * * * *

Ansel Conrad Morgenstern

August 9th 1892 to February 22nd 1939

Accomplished Auror, Beloved Husband, Overindulged Father

Perished fighting for a better world

Never Forgotten

**Notes for the Chapter:**

> Why am I sad about the death of a character that a few days ago did not even have a name?  
> If anyone enjoyed Ansel, I might one day write something else about him!
> 
> I promise!
> 
> Any thoughts about what can be the Advantage of Rotterdam Morgenstern?


	3. Reinstatement

**Summary for the Chapter:**

> How the Morgensterns cope with Ansel's death...

Ansel’s death was devastating for Marbella. Marbella knew this could happen. When she met Ansel, he was already an Auror, an amazing one. He was always so diligent and careful. She could count on one hand the number of times she went to see him at St Mungo’s in the almost 20 years he had been with the department.

_“Fighting for a better world for you and Rotterdam, Liebe,” he told her every morning after finishing his cup of coffee, before leaving the house._

And she could not believe it she would hear it no more. She stayed in bed, in the dark, for long hours after coming from the memorial, trying to sleep, trying to forget what had just happened.

* * * * * * * * * *

It was all a blur in Rotterdam’s mind. A man had come to tell them that unfortunately, his father had died while duelling a group of Acolytes. Mindy had helped him dress in some very stiff robes, and he held his mother's hand all through the ceremony. 

_“Schatz, if one day something happens to your old Vati, you must promise me you will always take care of your mama” Ansel would tell him, whenever they were alone._

When Marbella disappeared to her bedroom, as soon as they arrived home, he made to follow her, but Smudge stopped him and instead brought him his favourite desserts, telling him how his mother needed to be alone. 

Mindy put him to bed, but the boy could not sleep. And so, as silently as he could, he walked into his parents’ room, climbed into the bed, and nestled himself beside his mother, stroking her hair. “We will be okay, mama, we will be okay.”

* * * * * * * * * *

The first few weeks were horrendous, but little by little, using his inherent charms to his advantage, Rotterdam Morgenstern was able to help his mother to climb away from the darkness and the loneliness she felt.

“Mama, will you watch me from the balcony as I fly a little outside?”

“Mama, will you enchant the quaffle so I can train?”

“Mama, will you come and enjoy the sunset from the balcony, while I hover beside you.”

“Mama, will you have breakfast with me outside.”

“Mama, I believe something has happened to Zugspitze” That one made her run out of the house and into the owlery to check her favourite owl.

“Mama, I believe I’ve outgrown my robes. Will you come to Diagon Alley to help me get some new one’s.” 

Truth be told, he had cut them to make them look shorter. But it was worth it because they had Floo to Diagon Alley and into one of the robes shops, his mother's favourite. And he had been able to convince his mother to have some coffee at Carkitt Market with him since they were already at Diagon Alley.

Later that day, when they arrived home, Marbella did not return to her quarters, she stayed behind and went to the piano to play.

* * * * * * * * * *

Marbella made an effort to visit more friends and acquaintances and invite them over to Morgenstern Manor, all because of her son. Ansel would never forgive her, whenever they meet again, if she would seclude herself and her son away from society as his mother had done to him.

So, she sent letters to all her contacts, whoever she knew and had children in the same age group as Rotterdam. And during that year and a half before Rotterdam received his Hogwarts letter, she gave him all the advantages she could. Maybe he would not need these friends in his youth, but they could be useful for his adulthood.

* * * * * * * * * *

On the day of his 11th birthday, Rotterdam received his Hogwarts Letter, and he and his mama read it together, every word, slowly.

She kissed his cheek “Your papa would be so proud, my Rotte, attending Hogwarts. I’m so proud of you.” 

“I’m very happy to go to Hogwarts, but, mama, I don’t know how I feel about you staying here all alone.”

“Oh, sweetheart, No, no, no,” she said, kissing his forehead, once, twice, so many times until she gathered her thoughts “No, Rotterdam, No. Mama will be okay. It’s not your duty to care for me. I will write to you every day and I promise I will keep meeting my friends, many of them are also sending their babies for Hogwarts, so we will keep meeting for tea or coffee” she assured, “now get ready, my love, because the party will start soon.”

The Birthday Celebration was wonderful. Marbella had made all the Occamy decorations by herself, just to make sure everything would be perfect. It was not a big group, 8 other boys around Rotterdam age, their parents, and some siblings.

Alastor Moody, Horatio Prewett, Fingal Dearborn, Osbert Travers, Maxwell Parkinson, Raynor McKinnon, Gerry Macmillan & Oscar Fletcher, those were the boys who had played Quidditch, the enchanted safer version Ansel had made, and Wizard Skittles outside. Exploding Snap and Gobstones had mounted stations on the drawing-room. There were tables of finger food and other refreshments through the house. 

At the end of the day, Marbella had tucked her exhausted son into his bed, stroking his hair. “Did you enjoy your birthday party?” she asked.

“Very much, thank you, mother!” he said with a huge smile. “I know you would have much preferred just the two of us having lunch and dinner.”

“No, no, sweetheart. Not anymore” she assured, kissing his forehead. “I quite enjoyed all the conversations I had with your friends’ parents.”

“They are not all my friends, Alastor is more like a cousin,” he said and stroked his mother's hand “I’m so glad you enjoyed it as well, mom, after all the work you had with all the Occamy ornaments.”

“And did you enjoy your present?” She asked, mentioning the new books about magical creatures that now rested on his nightstand table.

“I have not read them yet, so I don’t know if I enjoy all the books,” he said “but, I’m very excited about the new edition of Fantastic Beasts and Where to Find Them by Mr Scamander.”

“You shall tell me all the little differences between the editions… but do not stay up late reading, sweetheart!” she said getting up, a knowing look on her face. 

She stopped at the door watching the contempt smile on her son’s face as he picked the book from the nightstand to read, a few pages at least, or the whole book.

* * * * * * * * * *

September 1st came too soon in Marbella's opinion, she had the trucks ready weeks in advance, but the previous day she had gone through everything.

“Mother, we are ready, everything is ready to go!” Rotterdam assured, petting Scafell, the Morgenstern Great Owl he would take to Hogwarts as his pet. 

“Yes, and if you need anything, you write home and I will send it as quickly as I can,” she said.

“Yes, mother. I will write every day. Poor Scafell will get tired.”

“No, sweetheart, you don’t need to write back every day. You will have your friends and classmates and classes. And I just want you to enjoy Hogwarts as much as I did, and how much I’m sure your father would have loved it.” she said, stroking his cheek. “Mindy, Smudge, let’s go take our boy to Diagon Alley!”

Marbella had bought one compartment, for Rotterdam, because of Scafell. Great Gray Owls were not used to being caged, so she thought the compartment would be a good place for Rotterdam and the owl.

“This is it,” she said kissing his cheek. “So proud of you… whatever house the hat chooses for you, it will gain a wonderful wizard. I need you to promise me that you will enjoy it to the fullest, baby! You will make friends! And not just focus on your interests. Open your horizons! Learn a little bit of everything!”

He nodded “Love you, momma. I will miss you” he said kissing her forehead. And then turned to the house-elves “I will miss you both very much as well, Take care of momma!”

Mindy grinned, taking her mistress hand on hers “Of course, little master! And you learn very much at Castle School!”

“Always take care of mistress.” Smudge said, the oldest elf had come from the Moody household, “And young master… fly careful!”

“Of course. I’m always careful! I will see you all soon” And with those words, Rotterdam Morgenstern boarded the train and took refuge in his compartment. 

He let Scafell fly and stretch its wings as he read. He had left the door open as his mother had said, and the package of Halloren Kugeln, traditional German chocolate balls, open on the table. To call for friends, his mother had said.

He stayed alone most of the time until there was a knock on his door. A boy, about his age, that he did not remember ever seeing was at the entrance of the compartment.

“Hello!” Rotterdam said looking up from his book “Would you like to come in and have some chocolate?”

The other boy nodded “It looks delicious, had never seen anything like that!”

“They’re a German recipe, my grandmother’s” Rotterdam explained, “You can have a sit while you eat, you don’t need to stand at the door. I’m Rotterdam Morgenstern!”

“Orion Black! Nice to meet you, Rotterdam!”

**Notes for the Chapter:**

> I hope you enjoyed it!  
> And Rotterdam made a new friend, it seems!
> 
> The Black is having an important place in this fic! Do not doubt it!
> 
> Liebe - Love or dear;  
> Schatz - Jewel, gem or treasure.


	4. Brotherhood

**Summary for the Chapter:**

> How the Morgenstern and the Black Families became more entwined...

And from that moment forward, Rotterdam Morgenstern and Orion Black became as close as brothers. Well not exactly from that moment forward, first Rotterdam Morgenstern was sorted into Slytherin House. From that moment forward the two boys became as close as brothers.

But there was one more step until one could call himself a friend of Orion Black, and that was gaining the family approval, and by family, it meant the other 4 students from the Most Noble and Ancient House of Black: Lucretia Black, Orion’s older sister, and the other group of siblings, Walburga, Alphard and Cygnus.

It was easy to understand that Walburga Black was the dominating figure, not only in the family but in Slytherin, she was Slytherin Queen after all. 

“So, tell me, Rotterdam, Can I call you Rotterdam?”

“Of course, May I call You Walburga?”

“No… You can call me Miss Black” she claimed.

“Then you can call me Mr Morgenstern, Miss Black,” Rotterdam said, meeting the older girl's eye.

Walburga made a displeased sound but nodded. “So, tell me, Mr Morgenstern, why do you, from a minor family, think you are worthy of the companionship of Orion?”

“Miss Black, it does not matter where we stand in life, in society, we all deserve companionship. Family is one of the most important things in life, but friendship is as important. Friends are the family that you choose!”

Walburga rolled her eyes, but at her right, Lucretia winked at him. “Do you think we are only cousins or are we friends as well, Burgie?” she asked.

“Well, I can say our affiliation is more than family togetherness, we have some of the same values…”

“We have fun together, Burgie! And what if Orion wants to have a friend outside the group, that’s okay. You know my brother, he’s a little dweeb, if he wants to be friends with another little dweeb, that’s okay!”

“Please, Burgie!” Cygnus told his sister. “I truly cannot listen to Orion speak about History of Magic or Charms. If he has found someone who will talk with him, we shall thank them!” he added before turning to Rotterdam. “So, I vote to let Orion be friends with Rotterdam Morgenstern! Goodbye!” Cyg kissed his sister and older cousin on both cheeks and left.

“Well, since Cygnus started the vote. I vote yes as well. Mama always protects Orion so much; I think it will be good for him to have a friend he chooses for once. Instead of one chosen for him.” Lucretia said, “I have an encounter with a certain Ravenclaw, so I will see you all later.” she waved.

“Assuming you vote no, but Rion votes yes, that means that there’s no need for me to vote, right?” Alphard asked. “I have a meeting with Slughorn about some extra credit!” he winked “I hope you enjoy being friends within the Most Noble and Ancient House of Black, Rotterdam Morgenstern!”

“And we remained two!” Rotterdam announced after a few minutes of awkward silence. “Do you have anything else to tell me, Miss Black?” he asked

She got up, focusing her grey eyes on Rotterdam. “Such coarseness from a young boy, such disrespect… I will be here to help Orion once he realizes you are not the kind of person that the Heir of the House of Black deserves!”

“Goodbye, Miss Black! It was a pleasure.” Rotterdam said, bowing his head before walking out of the common room. 

“How was it?” Orion asked, leaning against the wall outside of the Slytherin dorm entrance. “Were they terribly rude or prejudiced? Lucy and Alphard both left, and they are the voice of reason…”

“They’re protective of you… that’s it,” Rotterdam explained. “They’re your family, but I’m your friend… we’re not mutually exclusive!” he added with a smile. “Want to come and see the new trick I’ve been teaching Scafell?”

“If he does not try to bite me again!”

“Next time wash your hands, Orion!” Rotterdam teased. 

* * * * * * * * * *

The boys became pretty much inseparable since the beginning of the first year. So, it was not really a surprise when during Christmas Holidays, a letter came with the seal of The Noble and Most Ancient House of Black. 

Marbella Morgenstern was a bundle of nerves. She had changed robes three times that morning. 

“Mother, you look beautiful!” Rotterdam said, “Why are you so nervous?”

“Sweetheart, it’s not every day one is invited to have tea with the Black Family,” she confessed, taking a deep breath and looking at the clock on the wall. “I know it’s so you and Orion can play for a bit, but meeting Mrs Black is a big deal,” she explained.

“She will love you, mother, everyone we meet loves you,” Rotterdam said. He was excited to go and see Orion again. “Did you made more Halloren Kugeln?” he asked.

Marbella nodded “Of course… I asked Smudge to wrap them as a gift.” she explained, straightening her robe skirt. “It’s time, are you ready?”

Rotterdam nodded, moving to the fireplace. And just a few seconds later they were at Grimmauld Place. Orion was waiting there, surrounded by two dark haired women and a blonde young girl. 

“Rotte!” Orion hugged his friend, “Mrs Morgenstern, it’s a pleasure to finally meet you, your son speaks very highly of you.” he said before turning to his family “My mother, Melania, and my sisters, Lucretia and Lyra.”

“The pleasure is all mine, Young Mr Black. Thank you so much for the invitation, Mrs Black, this is a lovely foyer” and then, she turned to the younger girls “And hello-”

Before she could continue, Lucretia Black had interrupted her. “I’m quite pleased to make your acquaintance, Mrs Morgenstern, but I must depart, I’m terribly sorry.”

“Depart? Where are you going, Lucy?” Melania asked her daughter.

“Timothea Flint is having a soiree at her home with some other girls, Walburga will be attending as well” Lucretia explained, showing her the letter she had received that morning.

Melania read the letter, a frown appearing on her face “But Lucy, I thought you could stay and entertain Lily while I and Marbella talked” she said before turning to the other mother in the room, a blush on her cheek. “I apologize vehemently, may I call you by your first name, Mrs Morgenstern?”

Marbella smiled “Of course, Mrs Black, you can call me by my given name.”

“Oh, please, call me Melania. Daughters are so much more trouble than sons” she explained before turning the blue eyes to her oldest daughter. “Are you sure you can't stay for a little longer, Lucy?”

“I’m sorry, mama, but I must go. I do not want to affront Timothea. I will be back as soon as I can. I promise!” she kissed her mother cheek.

“I, sincerely, wanted to get to know Marbella this afternoon, Lucy” her mother sighed.

Marbella interrupted. “I’m certain, Lyra won’t be a hindrance for our conversation,” she said with a large smile.

“See, mama, Mrs Morgenstern will love to know Lyra as well, the lightest of the Blacks.” she added, adjusting her hair “Farewell, Mama. Mrs Morgenstern, it was a pleasure” with some Floo powder, the older child was gone. 

And with the boys running upstairs to Orion, Melania led Marbella to the drawing-room. “Lyra, will you be okay playing with Montress while mama and Marbella talk?”

“Oh, no, Melania, let the girl be with us. You won’t be bored by grownup conversations, will you, perle?”

And the 5-year-old blonde girl, took Marbella's hand and grinning brought her inside and sat on a couch beside her. “I’m Lyra, Lyra Black.” Melania followed them with a smile, shaking her head. Of all her children, Lyra was, definitely, the more sociable.

From that moment forward, Melania Black and Marbella Morgenstern became close friends, almost as close as their sons.


	5. Mourning

**Summary for the Chapter:**

> In the Summer of 1942, The Black Family suffers a big loss.  
> The Morgensterns are there to help...

**Notes for the Chapter:**

> TW: Minor Characters Death

It was a lazy morning, in the summer of 1942. Rotterdam Morgenstern was helping his mother with the Morgenstern owls outside when a great horned owl appeared with a letter. 

“Greenwich!” Rotterdam called after the Black Family Owl “you don’t want a treat?” he asked, confused as the owl flew away. Greenwich loved the Morgenstern treats.

“Is it for me or you, dear?” Marbella asked coming behind her son to look at the parchment, over his shoulder.

“Both” he whispered, “and it’s Lucretia handwriting, I’m sure.” 

“Maybe it’s a wedding invitation.”

“What wedding?”

“Lucretia and the middle Prewet boy, Ignatius. They started the courtship formally in May, once Lucy turned 17.” she explained. “it is a little too rushed for a wedding, but she’s not my child-” 

Rotterdam had opened the letter and was reading as his mother devised her thoughts, but unfortunately, the letter did not contain a wedding invitation. “They’re dead!” the boy said, mouth wide open.

“Who’s dead?” Marbella asked, dropping the bucket with fresh meat on the floor.

“Melania and Arcturus Black… The mourning ceremonies started today with a vigil at Grimmauld Place” he said, and he was rushing inside “Mother, do you believe my mourning robes still fit me? You might need to enchant them a little…”

* * * * * * * * * *

The arrival at Grimmauld Place was as grim as Rotterdam had fathomed would be. He tried to rush upstairs to find Orion, his best friend, but Marbella stopped him with just a look. 

He followed his mother respectful to the drawing-room. Marbella shook hands offering condolences to the family members spread on the different chairs. And then her eyes fell on the couple sitting on one of the couches. 

"Lucretia!" Marbella rushed forward, truly not caring about appearance surrounded by all those aristocratic pureblood wizards and witches. 

The younger witch said nothing, just let herself be hugged by Marbella Morgenstern, who was doing her best to console her. Ignatius gave him a smile, the fiancé had not let go of Lucy, he kept one hand steady on her back.

"Orion is upstairs with Lily," Orion’s oldest sister said, looking at Rotterdam. The 13-year-old nodded, taking her words as permission, and rushed to the upper floor. 

When he found Orion's room empty, he crossed the hallway to knock on the room where the Lyra constellation was drawn in pastel pink. 

Orion opened the door, his grey eyes bloodshot. He placed a finger over his lips, signalling him to be quiet and pointed to the bed, where his younger sister was sleeping. Orion Black moved to the hallway, letting the door ajar in case Lyra woke. 

Rotterdam hugged his friend "I'm so sorry, Orion. How can I help?" What he wanted to know what had really happened, but that was not a question for that moment.

"I don't know how to be the man of the family, Rotte. I'm 13" he whispered. 

"you're not alone, you have your uncles, they can-" 

Orion shook his head "I was the heir of the mainline, I'm now the patriar-" 

"You can't be the patriarch figure of the Great House of Black at 13."

"It's what is expected of me…" 

"Orion, you have not even attended your OWL's, you can't just drop out of school to take care of the accounts and become a philanthropist now. You need to study and when you graduate you become the patriarch or whatever your clan needs of you." 

Orion smiled sadly, almost wishing it would be so easy as Rotterdam said.

"How… Did someone from the ministry come to tell you about your parent's death?" he asked, remembering his experience three years before. When an Auror had come to offer his condolences about his father death.

"Ignatius, actually. He was working at St Mungo's… he came and delivered the news to me and Lucy. He has not left since. I mean… is he still-”

“He was downstairs when I arrived just a little bit ago.” Rotterdam nodded.

“Good, Lucy truly needs him,” Orion said. “After he came, we sent letters to family and friends... And now we are here.”

Rotterdam nodded sitting down on one of the benches on the hallway. “Who told Lyra?”

“Burgie… neither Lucy nor I could get the words out” he sighed “looking back now it was probably a bad idea to let Walburga do it,” Rotterdam said nothing, but his facial expression meant no owl shit, Minister. “She was harsh, Lyra refuses to come down because she will not have people saying her parents are not coming back.”

Just before Rotterdam could answer, footsteps were coming up the stairs. “Mother!” Rotte said.

“Mrs Morgenstern!” 

Marbella smiled “I don’t suppose now you will start to call me Marbella, will you, Orion?” she asked, taking his hands on hers and giving a squeeze, “Rotterdam and I will be here for all you need.” she assured, “Do you believe I can check on Lyra?”

“If she will speak with you, she’s been giving everyone the silent treatment for hours,” Orion confessed, “Even me… and I’m her brother.”

“I will do my best!” she assured, turning to knock on the door. “Rotte, I called for our parliament, why don’t you and Orion go check on them,” Marbella said as she opened the door. “Lyra, it’s Marbella, may I come in?”

And before the two boys disappeared, there was a sniffle and an audible “Aunt Marby.”

* * * * * * * * * *

How Marbella was able to get the Morgenstern owls to arrive at Grimmauld Place was a mystery to another time, but the parliament did arrive and most of the guests on the house came outside to watch the reverence of the birds. Scafell moved forward, raising one wing to stroke Orion’s cheek and then Lucretia, to comfort the students it knew so well from Hogwarts. 

And the only reason Lucretia did not fall on her knees was Ignatius' arms supporting her. “I’m so sorry, Orion, so sorry!” 

A hiss and an arm gesture from Rotterdam made the owls form a circle around the two siblings, giving them some privacy from the other visitants.

“You have nothing to be sorry about, Lulu!” Orion assured.

“I’m older… I’m of age… I could drop out of Hogwarts and be home, taking care of Lyra.”

“Never say that, Lucretia Melania Black!” Orion said, all the fear on him dissipating. This was the Orion that Rotte most enjoyed being friends with the protective brother. “You will be the head girl in just a few weeks, you will follow your dream of becoming a healer alongside your future husband,” he said, hugging her “I’m so proud of you, Lulu, so but so proud of all you have achieved, how could I ask you to give up on all that?” 

Lucretia did not speak, she just hugged her younger brother as her life depended on it. “I love you, Orion.”

“We will be okay, we have many aunts and uncles to care for Lyra while we study,” Orion said, pulling back.

Ignatius nodded “Your brother is right, and once you finish your NEWT’s, and we get married, Lyra and Orion can come live with us.” he told his fiancée.

“Are you promising, Iggy?” she asked, pulling away from her brother and looking at him.

The red-headed nodded, kissing her forehead. “Of course, they are my family as well,” he explained.

**Notes for the Chapter:**

> For someone who hates to kill characters in Fanon... too many have died on my baby oc fic xD  
> Sorry!


	6. Corollary

**Summary for the Chapter:**

> Marbella and Rotterdam solve a problem...

**Notes for the Chapter:**

> [Murder_Kitten](https://archiveofourown.org/users/Murder_Kitten/pseuds/Murder_Kitten) Please forgive me for all the legal technicalities that I ignored. 
> 
> I hope you enjoy this last chapter as we finally discover what's the Advantage of Rotterdam Morgenstern.

On September first, Rotterdam Morgenstern goes back to Hogwarts, along with Orion and Lucretia. Lyra stays with Pollux and Irma Black, the parents of Walburga, Alphard and Cygnus Black, who attend Hogwarts as well.

The first term went well. Unsurprisingly, Lucretia is an excellent head girl, and the responsibilities keep her busy and focused. Rotterdam becomes part of the Quidditch Team, and he can only imagine how proud his father would be. Orion tries to become a hermit and study pureblood law, but unfortunately for him, his best friend is not pleased with the idea and does his best to keep him away from that damned section of the library.

The Children return from Scotland to spend Christmas with their families. Rotterdam receives a strange letter on Christmas Eve. 

“That face, Rotte, that face remembers me of the one your father used to make when he was working on those unusual cases,” Marbella said, looking up from her needlework.

“Orion has written to wish us a Happy Yule and to announce his impending betrothal,” Rotterdam said, levitating the letter and sending it to his mother.

Marbella was too shocked at first, Orion Black was 13 and the boy’s mother had never mentioned an impending engagement for her only son. And now that he was appointed head of the family, he would not be forced into one. Would him? “Is it someone you know from Hogwarts? Someone he was interested in? A schoolyard crush?”

“It’s not his choice, momma,” Rotterdam said with a groan, summoning some parchment and a quill.

“What do you mean it’s not his choice?”

“His uncle is asking him to marry Walburga, it’s the compensation required for taking care of Lyra while Lucretia does not finish school,” Rotterdam explained, his eyes on the blank parchment, trying to find the right words to answer his friend. ‘Thank you. You’re a fool’ did not seem appropriate.

Marbella let go of a series of profanities in German, Rotterdam turned to watch his mother, surprised. “How dare them! How dare they use a little girl like a bargaining chip to force another child into a marriage! How dare them!” 

“Smudge! Mindy! Bring us some tea or a calming draught!” Rotte called and soon after the elves appeared. “Drink, momma, please!” He told his mother, adding two cubes of sugar to her chamomile tea.

Marbella accepted the cup and drank slowly. “That was not what Melania would want for her children, for her son. What kind of family blackmails a child like this!” she shook her head and came to a decision. “I’m going to Diagon Alley. You stay home, and write to Orion. Tell him to not accept that contract! Tell him your mother is going to help.”

“Mother… How are you going to help?” Orion asked as she returned from the upper floor, changed into some formal azure robes.

“Do not doubt your momma, Rottie” She whispered and kissed his cheek. Marbella adjusted her hat and summoned her bag. “I don’t know when I will be home. See you later, sweetheart.”

* * * * * * * * * *

How Marbella Morgenstern did it was not important. She did it because it was the right thing to do. After all, she and Ansel had raised their son to be good, to believe in the good of the world, to believe each personal action could change the course of the wizarding world for the best.

“You have a flying car?” Rotterdam asked, surprised, as, a couple of days after Christmas, his mother lead him to a part of the Manor he did not even know existed, the Garage.

“I had quite some free time while you were at Hogwarts.” She said getting inside.

“Where are we going, momma? Why don’t we take the Floo?”

“Your father would call it a dramatic entrance,” she explained. “He would be so proud if he was here.”

“I have no idea what we are about to do, mother, but he is always proud of you,” Rotterdam assured, placing his hand over his mothers on the wheel of the car.

“Of us!” she corrected, kissing his cheek.

Soon after they were at Grimmauld Place, even before knocking on the door, it was opened for them. 

“Aunt Marby, you brought your car again!” Lyra exclaimed, wrapping her arms around the Morgenstern matriarch.

Marbella smiled “I did. I will even take you for a ride, but before I would like to speak with your brother, is he home?”

Lyra nodded, leading them to the office on the main floor. “Ori! Aunt Marby and Dam are here to see you! Did you get in trouble?” The young girl asked with a smirk.

* * * * * * * * * *

“I… I don’t understand, Mrs Morgenstern.” Orion said, looking at the papers in front of him. If Rotterdam was being honest, he had not understood until Marbella explained a couple of minutes ago, but he would not share that with Orion.

“Mother is alone, Orion, all the time we are at Hogwarts, she’s alone at the Manor with the elves. And she loves you and Lyra and Lucretia like her own family, you are the nephews she loves the most.” Orion nodded as he heard his best friend.

“Orion, you know that when you and my son became friends, in a way so did I and Melania. As you can imagine, Mother conversations are usually around their children and the plans they have for them.” Marbella said. “She told me how she detained the betrothal arrangements for you and your siblings because she wished for all of you to marry who you wanted and not someone imposed on you. Your mother was one of the great ones.”

Marbella took one more sip of her tea, smiling at the young boy, who was looking at her. His grey eyes were a mix of emotions, sadness, distress, duty, hope. “I know I’m not family, not by blood. But, I would love to take Lyra in, while you and Lucretia are at Hogwarts. I’m not trying to usurp your mother’s place, never! I just want to facilitate your life, all of yours.”

Orion sighed, he wanted to say yes so badly. “Mrs Morgenstern, I could not possibly impose… my sister, my responsibility.”

“I’m not trying to take that responsibility from you, Orion.” she said summoning another folder from her bag “I have a contract, you’re still responsible for your sister while she’s not of age, you're only letting her live at Morgenstern Manor when neither you nor Lucretia is available. Just that. All the choices will be yours. You will always have the final say.” 

“So my sister will still be cared for, and there will be no betrothal arrangements,” Orion concluded, his eyes moving through the ink on the top of the new piece of parchment. The Matter of the Care of Lyra Elladora Black.

“It’s all stipulated there, Mr Black.” Marbella used his title, hoping the mention of it would make him feel a little more powerful and able to make a choice. The right choice. 

“Thank you,” he said, opening the folder. “I will read over this and make a decision.”

Rotterdam almost choked on his tea, rolling his eyes at his best friend. Only Orion Arcturus Black would deny himself the chance to jump into the right path right away. “Deliberate all you want, Orion. But do not forget to take your sisters’ opinions into account as well.”

Orion nodded. “Thank you, Rotte. Thank you, Mrs Morgenstern.”

“Come, Rotte. Give some time to your friend to think. It’s not an easy decision, trusting someone you love into someone else's arms.” Marbella pointed out with a soft smile.

In the end, Orion accepted the proposition, of course, he did. And Lyra was enthusiastic about living in Morgenstern Manor. She had visited with mama multiple times before, but this time was different, she was going to live there while Lu and Rion were at Hogwarts. 

Morgenstern Manor was so different from Blackood Estate where Uncle Pollux and Aunt Irma lived. It was lighter and more modern. And loving. Lyra was certain she would be happy there.

Oh, and there were so many owls.

* * * * * * * * * *

That was Rotterdam Morgenstern’s biggest advantage. His family. How he was raised to be compassionate and reliable, to protect those he loves and chooses to stand beside him.

So maybe, The Advantage of Rotterdam Morgenstern was not his own. Maybe Rotterdam Morgenstern was an Advantage on Himself. Having him on your side would always be Advantageous.

**Notes for the Chapter:**

> I hope you enjoyed this little story. OC's are always fun to play with <3  
> The plan was always to mix the Morgensterns and The Noble and Most Ancient House of Black <3
> 
> And I shall have more one day soon <3


End file.
